Journal Title (Medline/Pubmed accepted abbreviation): Nutrition.
Page numbers: 451-455
doi (if applicable): 10.1016/j.nut.2010.04.001
Summary of Background and Research Design
Background: Creatine is a very common ergogenic supplement used in a variety of sports. A common method of beginning supplementation is creatine-loading, where an athlete consumes about 20-25 g of creatine per day for 5-7 days in order to rapidly increase muscle creatine stores in their body (typically 5 g 4 times per day), before reducing the dose to a maintenance level of 3-5 g once per day for an indefinite period of time.
Hypothesis: A low daily dose of creatine, taken over 6 wks, will increase creatine concentration in the body, improve performance, increase lean body mass, and overall improve muscle function without creatine loading.
Subjects: In total, 12 male and 8 female omnivores (meat-eaters) about 18-23 yrs old, participated in this study.
Experimental design: randomized, double-blind, placebo-controlled design
Treatment: Every day for 6 wks, subjects consumed 0.03 g creatine monohydrate or placebo per kg of body weight with food (to maximize absorption). This dose of creatine is equal to 2.3 g/day for a 75-kg (165 lb) person. The identity of the placebo was not disclosed
Protocol: Baseline measurements were acquired at visits 1 and 2, separated by 1 wk, to assure the reliability of the measurements. Measurements included height, weight, total body lean mass and fat mass, muscle strength (highest peak torque during a 3-repetition concentric knee extension), and muscle fatigue (5 sets of 30 concentric knee extensions with 1 min to rest in between sets; peak torque was assessed for each sets and compared to set 1). A blood sample was acquired to measure plasma creatine. After the 2nd baseline sample, subjects consumed the creatine or the placebo for 6 wks. Then, they returned to the laboratory (visit 3) and underwent the same measurements as the baseline visit.
Summary of research findings
- The concentration of creatine in the blood increased significantly after creatine supplementation (p = 0.03).
- Creatine supplementation did not affect body weight, fat free mass, fat mass, body fat percentage, or total body water (p ≥ 0.19)
- Creatine supplementation did not increase maximal strength, as measured by peak knee extension torque
- When performing 5 sets of leg extensions, peak torque decreased from sets 1 to 5 in all sessions, indicating fatigue. Those supplemented with creatine were more resistant to fatigue (p = 0.03).
Interpretation of findings/Key practice applications
About 2.3 g of creatine per day for 6 wks an increase resistance to fatigue without inducing weight gain. Therefore, a creatine loading protocol, where an athlete consumes 20 g creatine per day for 5 days, is not necessary for this particular ergogenic effect. This may have benefit for athletes participating in sports in which ergogenic effects without increases in body weight (e.g., wrestling, boxing) are important.
The prior training status of the subjects was not stated and it does not appear that there was a structured exercise program during the period of creatine supplementation. Therefore, we cannot make any conclusions as to how creatine supplementation affects body measures or muscle function in an active person or in combination with any specific workout routines. It would have been interesting to see if the results would have been similar had a particular training program been added during the creatine supplementation. In addition, the authors did not measure muscle creatine stores to determine if the period of supplementation was effective at increasing muscle creatine levels.